Conventionally, systems have been considered that enable a telephone number to be updated with ease when the telephone number is changed such as when the model of the mobile terminal, such as a cellular telephone, is changed. For example, Patent Document 1 discloses making various settings to automatically notify, at a set time, parties identified by a user, via a text message regarding the change of telephone number, displaying a confirmation of the text message notifying the desired partner of the change of telephone number. According to this system, the user is capable of notifying a plurality of communicating parties of a change of telephone number of the user without needing burdensome operation. [Patent Document 1] Japanese Laid-Open Patent Publication No. 2002-247182